Previous studies have reported the absence
of a contagious effect when autistic children
view another's yawning. This result could be due
to the difficulty of autistic children in
establishing reciprocal gaze behaviour with
human partners.

Furthermore, the presence of a contagious
effect in autistic children could change
according their degree of functioning. We
evaluated the contagious effect of yawning in
both autistic children with different degrees of
functioning and in typically developing children
exposed to the viewing and hearing of others
yawn.

Furthermore the frequency and the daily
distribution of spontaneous yawning were
evaluated and compared among three groups.
Autism Spectrum Disorder can selectively affect
some behaviour. In autistic children the
contagious effect of yawning is largely
impaired, whereas the spontaneous production and
daily distribution are not. These results
support the hypothesis of a link between
contagious yawning and social abilities and the
existence of different processes underlying
spontaneous and contagious yawning.

Yawning is a widespread spontaneous
behaviour observed not only in humans but also
in several animal species (Baenninger,
1997; Walusinski
& Deputte, 2004). The role and function
of the yawn vary according to the animal's place
on the phylogenetic scale (Ficca &
Salzarulo, 2002). In low evolutive species,
yawning seems to be involved in homeostatic
processes, whereas in high evolutive ones
(mammals and primates) yawning could be linked
to environmental needs (increased vigilance
level; danger; hunting prey), or even
communicative ones (sign of aggressiveness,
hierarchic dominance, frustration, sexual
excitement, means of synchronised activities
within the group).

The phase-shift between the emergence of
spontaneous and "contagious" yawning could
suggest separate processes underlying the two
kinds of yawning, apparently similar, but
probably different in their meaning. Previous
studies on anencephalous newborns able to yawn
proposed that the brain's archaic structures
were involved in spontaneous yawning occurrence
(Price Heusner,
1949). More recently (Daquin,
Micallef, & Blin, 2001), clinical and
pharmacological studies indicated that several
anatomical structures are implicated in the
control of yawning, such as the hypothalamus
(mainly the paraventricular nucleus), bulbus,
pontic regions, with frontal region connections
in primates and to the cervical medulla.

In particular, Senju and colleagues (2007)
report the absence of a contagious effect when
autistic children view others yawn. The absence
of contagious yawning in autistic children
reported by Senju's study could be due to the
their difficulty in establishing reciprocal gaze
behaviour with human partners (Volkmar &
Mayes, 1990). Indeed, autistic children look at
others less frequently (Swettenham, Baron-Cohen,
Charman, Cox, Baird, & Drew, 1998) and show
deviant use of reciprocal gaze
(Willemsen-Swinkels, Buitelaar, Weijnen, &
van Engeland, 1998). Furthermore, the presence
of a contagious effect of yawning in autistic
children could depend on their degree of
functioning and low-functioning autistic
children could show a greater impairment in
yawning contagiousness with respect to
high-functioning autistic children.

The aim of this study was to evaluate the
contagious effect of yawning in autistic
children with different degrees of functioning
(high vs low functioning) and in typically
developing children using two different
modalities: the viewing and hearing of another
person yawning. Furthermore, in order to avoid a
bias arising from possible differences among
groups in spontaneous yawning production, the
frequency and the daily distribution of
spontaneous yawning were evaluated and compared
among three groups.

DISCUSSION

Our results showed that spontaneous yawning
was not impaired in autistic children. In both
HFA and LFA children the daily yawn frequency
was similar to that observed in TD children. In
addition, daily yawn distribution in autistic
children corresponded closely to the daily
distribution not only of TD children but also of
adult people (Provine, Hamernik, & Curchack,
1987; Baenninger, Binkley, & Baenninger,
1996). Indeed the number of yawns was high
during the morning, decreased in the afternoon
and increased in the evening approaching onset
of sleep. Different from spontaneous yawning,
contagious yawning seems to be impaired in
autistic children. Indeed, typically developing
children yawned more watching or hearing others
yawn than both HFA children (only one of them
yawned observing others yawn) and LFA children
(none of them yawned either observing or hearing
others yawn).

This result does not depend either on the
differences of spontaneous yawning among the
three groups or the differences of spontaneous
yawn distribution during the daytime. Consistent
with previous data (Senju et al., 2007), our
results showed the absence of contagious yawning
in autistic children when they view others
yawning. The contagious effect of yawning during
the listening to of others yawning was also
impaired in these subjects. This result is
contradictory to our hypothesis that autistic
children's difficulty of establishing a
reciprocal gaze behaviour with their caregivers
and other people (Volkmar & Mayes, 1990)
could affect the contagious effect during the
observation, but not during the listening to of
others yawns.

Therefore, our data pointed out that a
specific disorder such as ASD can selectively
affect some behaviours such as yawning. Indeed,
whereas the spontaneous production of yawning in
autistic children appeared to be preserved,
yawning in response to the observation or to the
listening to of others yawning was largely
impaired. This result together with the
phase-shift between the emergence of spontaneous
and that of "contagious" yawning, contribute to
bear out the hypothesis of separate processes
underlying the two kinds of yawning. The absence
of contagious yawning in autistic children and
the impaired capacity for empathy reported in
these subjects (Baron-Cohen, Knickmeyer, &
Belmonte, 2005) support the widespread proposal
(Anderson et al., 2004; Platek et al., 2005;
Schurmann et al., 2005) of a link between
contagious yawning and social abilities such as
self-awareness and mental state attribution that
show an atypical development in ASD (Leslie
& Frith 1988; Baron-Choen, Leslie, &
Frith,1985).

It is unlikely that the absence of
contagious yawning in autistic children could be
due to impairments of imitative abilities or of
the mirror neuron systems involved in action and
intention understanding found in these subjects
(Dapretto, Davies, Pfeifer, Scott, Sigman,
Bookheimer, & Iacoboni, 2006). In this
regard, it is noteworthy to observe that
autistic children are able to mimic behaviours
such as smiles and laughter in our "control"
conditions. Indeed, even if the evaluation of
the contagious effect of laughing was not our
main aim, we observed that in the control
condition high functioning autistic children
tend to smile more watching others smile than
watching others yawn (z= -1.84; p=. 06) and
laughed more listening to others laugh than
listening to others yawn (z=-2.03; p= .04).
These results could be interpreted also taking
into account the proposal to consider empathy a
"collection of partially dissociable
neurocognitive systems" (Blair, 2005, pag.
698).

In particular three different levels were
described: cognitive, motor and emotional
empathy. Cognitive empathy refers to the ability
to represent the mental state of others; motor
empathy refers to the capacity to automatically
mirror vocalizations, facial expressions and
motor behaviours of another person and finally
emotional empathy refers to the recognition and
response to emotional expressions of other
people, as well as various other emotional
stimuli. Autistic subjects were found to be
impaired with respect to both cognitive and
motor empathy, whereas they seemed to show less
difficulties with respect to emotional empathy
(see Blair, 2005 for a review).

The sensitivity to the contagiousness of
yawning could reflect cognitive empathy and the
absence of contagious yawning in our sample
could confirm the impairment in cognitive
empathy previously reported in autistic
subjects. Moreover, the response to others
laughing and smiling (probably reflecting
emotional empathy) observed in high functioning
autistic children, but not in low functioning
ones, not only supports data about the presence
of emotional empathy in autistic subjects, but
also suggests different levels of empathic
capacities according to the degree of
functioning.

Finally, the contagious effect of yawning
was confirmed in typically developing children
in agreement with previous results showing this
effect in younger children (Anderson & Meno,
2003). Furthermore, this is the first study to
show the contagious effect of yawning in
children listening to others yawn. It is
interesting to observe that the percentage of
contagious yawning found in typically developing
children was higher than the percentage reported
by Provine (2005) in the young adult. Indeed,
whereas in our study 70 % of children yawned
watching others yawn, only 55% of young adults
yawned (Provine, 2005) while observing yawns.
Maybe children are less subject to the social
inhibition of yawning than young adults. Indeed,
Provine (2005, p.539) reported that "even highly
motivated and prolific yawners [...]
stopped yawning when placed before the camera"
of a national television.

In conclusion, our study showed that ASD can
selectively affect some behaviours. In autistic
children the response to yawning, both viewed
and listened to, is largely impaired, whereas
the spontaneous production and daily
distribution of yawns is not. These results
support the hypothesis of a link between
contagious yawning and social abilities and the
existence of different processes underlying
spontaneous and contagious yawning.